Deep-water strata of the Neoproterozoic Kaza Group and Isaac Formation (Cariboo Group) in the southern Canadian Cordillera (B.C.) were deposited in a passive-margin basin during the break-up of supercontinent Rodinia. At the Castle Creek and Mount Quanstrom study areas, a remarkably continuous stratigraphic interval throughout these units preserves a record of basin-floor overlain by strata deposited in the lowermost part of the slope. Although similar stratal intervals have been described from ancient and modern deep-marine settings, they still remain poorly understood.
Three main stratal units are recognized within the study areas. The lower unit consists of three channel-lobe systems formed in the basin floor to slope transition. Uniquely, siliciclastic-dominated strata here consist of a variety of small- and few large-scale scour elements, indicating transport bypass along the channel-lobe transition zone, in addition to detached or attached depositional lobes composed mostly of distributary channels, fine-grained deposits, and uncommon splays, and a rare slope leveed channel complex. The middle unit is a siliciclastic-dominated succession of stacked, km-scale mass-transport deposits (i.e. debrites and slides), which indicates the more frequent emplacement of increasingly larger mass failures on a prograding slope, and are overlain by fine-grained, splay deposits that are successively overlain by channel, ponded and fine-grained deposits. In contrast, the upper unit is a mixed siliciclastic-carbonate slope succession of the first Isaac carbonate, a regional marker horizon that comprises mostly carbonate-rich and siliciclastic-rich fine-grained strata intercalated with channel and gully complexes that are mostly filled with coarser-grained strata.
Abrupt changes in facies trends, stratal stacking patterns and depositional styles throughout these units are largely linked to long-term changes in relative sea level and its control on sediment supply, namely sediment caliber, volume and mineralogy. Notably, in the upper unit, small-scale changes in sediment source and supply are related to shorter sea-level variations superimposed on the long-term eustatic change.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/35023 |
| Date | January 2016 |
| Creators | Navarro Ugueto, Lilian Leomer |
| Contributors | Arnott, Robert W.C. |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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